Recent studies have demonstrated that brain angiotensin II receptors may have importance in the development and maintenance of experimental renal hypertension. The objectives of the proposed research are to determine (A) the effects of angiotensin II infusion into the cerebrospinal fluid (lateral ventricle) on renal function inconscious rats. (B) the role of changes in renal sympathetic nerve activity on renal function during intraventricular angiotensin II infusion and (C) the effect of altered dietary sodium on changes in renal function during intraventricular angiotensin II infusion. Five specific aims have been proposed for study: 1) Does intraventricular infusion of angiotensin II at doses which are both above and below the threshold for increasing arterial pressure alter arterial plasma renin activity, effective renal plasma flow, glomerular filtration rate or urinary sodium excretion in conscious rats? 2) Do the changes in renal function and plasma renin activity which occur in response to intraventricular angiotensin II infusion result from direct activation or angiotensin II receptors in the brain? 3) Do the changes in renal function and plasma renin activity during intraventricular angiotensin II infusion result from altered renal efferent nerve activity? 4) What is the effect of altered sodium chloride diet on the changes in plasma renin activity and renal functional changes observed during intraventricular angiotensin II infusion? 5) Is there a modulating influnce of alpha and/or beta adrenoceptors in the brain on the renal functional changes elicited by intraventricular angiotensin II infusion? Experiments will be conducted in conscious, unanesthetized rats. Renal function and plasma renin activity will be assessed before and during intraventricular angiotensin II infusion at subpressor dose using renal clearance techniques. The effects of angiotensin II, alpha and beta adrenoceptor blockade and renal dernevation on the renal functional response to intraventricular angiotensin II infusion also will be determined. The sympathetic nerves and renin-angiotensin system are important factors in the regulation of peripheral resistance, blood volume and arterial pressure. The long-term goal of this study is to develop a better understanding of the effects of brain angiotensin II in the control of renal function and consequently the influence of brain angiotensin II on the regulation of arterial pressure.